1. Field of the Invention
The present invention relates to a high-density recording and/or reproducing apparatus applying a scanning probe microscope, and more particularly to an information recording and/or reproducing apparatus for recording and/or reproducing information with probes being in contact with a recording medium.
2. Description of the Related Art
Recently developed is a scanning tunneling microscope (hereinafter referred to as STM) with which a surface of a conductive material can be observed with a resolution below nanometers, as described in U.S. Pat. No. 4,343,993. Such STM is used to observe an arrangement of atoms on a surface of a metal or a semiconductor, orientation of an organic molecule, etc. in the atomic or molecular scale. Developing the STM technology, an atomic force microscope (hereinafter referred to as AFM) which could observe surfaces of insulating materials, etc. with the same resolution as that of STM was also developed (U.S. Pat. No. 4,724,318).
Applying the principle of the STM, such techniques are proposed that a probe is made to gain access to a recording medium in the atomic or molecular scale and that in that state recording and/or reproduction is carried out, achieving a high-density memory (U.S. Pat. No. 4,575,822 and Japanese Laid-open Patent Application No. 63-161552 and No. 63-161553).
Further, concerning a high-density memory and a structure of an apparatus being a combination of STM with AFM, there are proposed a recording and/or reproducing apparatus in which STM structure is used to apply a voltage between a tip and a recording medium so as to effect recording and AFM structure is used to detect the shape of recording bits so as to effect reproduction, a recording and/or reproducing apparatus in which the principle of AFM is applied to control a position of a tip in recording and in reproduction, and a recording and/or reproducing apparatus in which a tip is arranged to trace the surface of the recording medium in recording and in reproduction, utilizing deformation of an elastic member supporting the tip (Japanese Laid-open Patent Application No. 1-245445, No. 4-321955, and No. 5-040968, which matured from Japanese Application No. 3-194124).
Among the above conventional examples, the recording and/or reproducing apparatus having the arrangement of an apparatus in combination of STM with AFM is so arranged that recording or reproduction is performed with the tip being in contact with the recording medium. Where a voltage for recording is applied between the tip and the recording medium while keeping the tip in contact with the recording medium, an electric current flowing during recording sometimes breaks the tip, because it is difficult to control a value of the flowing current in the contact state. In addition, because of the contact arrangement between the tip and the recording medium, there are cases where a fragment of the recording medium is deposited on the tip due to the breakage in recording. As a result, the tip is contaminated, which caused problems of decreasing the resolving power of the tip, decreasing the conductivity of the tip, and decreasing the reliability of recording or reproduction. The present invention has been accomplished to solve the above problems.